Although the interest for equity is growing, scanty attention has been reserved so far in Italy to health care inequalities. The relation between hospitalization and socioeconomic position in Rome has been studied by evaluating overall heterogeneity and differences in access to effective non-discretionary treatments or at high degree of generic or specific inappropriateness. An area-based socioeconomic index was assigned to 86.4% out of 554.168 discharges of Rome residents identified during 1997 through the hospital information system. The analysis was performed by comparing standardized hospitalization rates across socioeconomic groups through linear trends and risk ratios. A significant inverse relation of overall hospitalization with socioeconomic position was observed for both acute admissions (+44% for most deprived males) and day hospital (+25%). No difference was found in use of effective treatments such as admissions in coronary care units for acute myocardical infarction or surgery for hip fractures. The inverse relation between socioeconomic position and acute hospitalization blunted in day hospital for inguinal hernia repair and actually reversed for cataract removal among females. The hospitalization risk for minor skin diseases, an ambulatory care sensitive condition, resulted inversely associated to socioeconomic position. An excess of hospitalization was also observed for poorest females undergoing appendectomy. Results indicate that observed heterogeneity between socioeconomic groups does not depend only on different health needs but also on an unequal utilization of services: although disadvantaged groups have equal access to treatments of non-discretionary effectiveness, they hardly use innovative services and are more vulnerable in receiving unnecessary treatments.